Convert FLAC to AAC Online
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FLAC (.flac) · Max 20 MB
AudioUtils converts FLAC to AAC using WebAssembly. The entire process happens locally. No upload, no server, no waiting in a queue.
Open any browser. Pick your file. Click convert. The AAC file downloads instantly. Works on any device with a modern browser.
FLAC is lossless. Converting to AAC reduces file size at the cost of some audio data. Use a high bitrate to minimize loss. Free tier handles input files up to 20MB file size limit with a 10-second preview output. Upgrade to Pro for unlimited, full-length conversions up to 500MB file size limit.
Frequently Asked Questions
What AAC bitrate should I use from FLAC?
256 kbps (VBR or CBR) for archival-quality AAC — matches Apple Music's stream rate, near-transparent on almost any music. 192 kbps is the everyday sweet spot — small files, excellent quality, suitable for the bulk of music libraries. 128 kbps for voice content and audiobooks. AAC is more efficient than MP3, so 192 kbps AAC sounds about as good as 256 kbps MP3.
Will the AAC sync to my iPhone via Apple Music?
Yes. AAC files (in M4A containers) sync through Apple Music / iCloud Music Library to iPhone, iPad, Apple Watch, and Apple TV. FLAC does not sync this way. Conversion to AAC is the standard step for getting a FLAC library onto Apple devices.
Is the output a .aac or .m4a file?
Our output uses the M4A container (AAC inside MP4) with the .m4a extension — this is what iTunes, Apple Music, and iPhone expect. The audio inside is identical to a raw .aac stream; only the wrapper differs.
How much smaller will the AAC be?
Roughly 80–85% smaller than the FLAC source for typical music. A 40 MB FLAC track becomes a 6–8 MB AAC at 256 kbps, or 4–5 MB at 192 kbps. Hi-res FLAC (24-bit / 96 kHz) shrinks even more dramatically since AAC operates at 16-bit / 48 kHz.
Will metadata transfer?
Common tags (title, artist, album, year, genre, track number) transfer cleanly from FLAC's Vorbis comments to M4A's iTunes-style atoms. Album art transfers. Some specialised tags (composer, conductor, BPM) may need re-tagging in iTunes or MusicBrainz Picard for curated libraries.
Should I use ALAC instead of AAC?
If you want to keep the lossless quality on Apple devices, use ALAC (Apple Lossless), not AAC — same quality as FLAC but Apple-native. Use AAC only when file size matters more than absolute quality (which is true for portable playback on most listeners).
About FLAC
Lossless compression. Perfect quality at roughly half the size of WAV. The choice for audiophiles and archiving.
About AAC
Advanced Audio Coding. Successor to MP3 with improved compression. Widely used in streaming services.